U.S. Pat. No. 5,040,833 to Brunnert discloses a closing device for drawers and includes a drawer installed to a piece of furniture and the drawer is movable between a closed position and an opened position. A spring is located between the drawer and the furniture. A switch device is connected to the furniture and includes a holding member which includes a hook, and a latch member is connected to the drawer. When the drawer is in its closed position, the latch member is engaged with the hook of the holding member. The latch member includes at least one upper portion which defines two guide tracks to guide the holding member. When the drawer is opened or closed relative to the furniture, the holding member is bent by the guide tracks. When the drawer is pulled out from the furniture by force, the holding member is bent upward so that the hook is disengaged from the latch member. When the force pushes the drawer to its closed position, the hook is movable and releases the engagement with the latch member so that the drawer responses the resilient force and pops out from the furniture.
U.S. Pat. No. 7,374,261 to Wang discloses a push-open type slide structure which comprises a top fastener and a locking device mounted between an outer slide rail and a pull rod. The top fastener comprises a loading plate extending from one side of a center portion of the main body thereof. Two pillars extend from both sides of the main body respectively. An action trench is formed on a connection portion between the main body and the loading plate. The action trench is in communication with a holding trench on the backside of the main body. A second elastic device is mounted on the inside of said holding trench. The loading plate has a shaft hole and a slideway on a surface and slide rails on the backside of the loading plate. The positioning fastener has a shaft and a protrudent part on a bottom surface, a hook on an inner edge, and a guide pillar on a rear end. The shaft of the positioning fastener is held in the shaft hole. The protrudent part is exactly coupled, with the inside of said slideway. The hook is inserted into said action trench of the main body and coupled with the second elastic device. The pair of first elastic device is sleeved onto the pillars of the main body. Two sleeves are mounted on both sides of the slide sleeve and coupled with the pair of first elastic devices respectively. The slide sleeve is coupled with a lower portion of the loading plate. The slide sleeve is slidable on the slide rails of the loading plate. The locking device is fixed on said pull rod. The locking device has a connection part for coupling with a guide part and a shaft holder. The guide part of the locking device has a guide edge, an inclined plane, and a recessed trench. The shaft holder has an edge protrusion spaced from the recessed trench by a certain distance so as to a form a tunnel.
Both Brunnert and Wang disclose a means to prevent from damage when the drawer is forced to open. The means for Brunnert uses the upward bending of the holding member to disengage the hook from the latch member. Wang uses the space located beneath the guide pillar so as to allow deformation of the holding trench such that the pillars can be disengaged from the locking device. However, both disclosures use the flexibility to achieve the disengagement and wearing happens during operation and may cause permanent deformation to the relative parts and this reduces the lift of use of the whole slide assembly.
The present invention intends to provide an opening device for slide assembly and the opening device of the present invention improves the inherent shortcomings of the conventional disclosures.